Fig. 1.

Metric interactions in transit flocks and topological interactions in mobbing flocks. a Jackdaw trajectories in a sample transit flock. b Jackdaw trajectories in a sample mobbing flock. c Alignment angle between a focal bird and its neighbours. d, e Anisotropy factor γ for the distributions of neighbours relative to a focal bird for d mobbing and e transit flocks. r is the distance between the focal bird and its neighbour, and n is the topological rank. In a, b coloured lines show the jackdaws’ three-dimensional (3D) trajectories, and the black dots show their positions in flocks at the final time step. The grey planes are arbitrary horizontal planes (that is, perpendicular to the direction of gravity). Data in c, d are calculated from 10 mobbing flocks and 6 transit flocks. Standard errors are smaller than the symbol size